Lead poisoning can produce severe brain damage in young children. Pathologic examination of the nervous system reveals massive brain edema, probably related to capillary damage. We propose to establish the metabolic basis for brain capillary injury by lead. Acute lead encephalopathy will be produced in young rats and the formation of brain edema will be determined by measuring the sodium and water content of the brain. Capillaries will then be isolated from the brain of these animals by a method developed in our laboratory. Controls will consist of capillaries isolated from adipose tissue in the lead poisoned rats as well as capillaries isolated from normal rats. The effect of lead exposure upon the enzymatic, transport and histologic characteristics of the isolated brain capillaries will be determined. In addition, we will search for changes in the metabolic activity of brain capillaries during development that may explain the vulnerability of immature brain to the toxic effects of lead.